Quick Reference Guide

PowerConnect B-Series TI24X Configuration Guide 325
53-1002269-02
Dynamic link aggregation
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Link aggregation support is disabled by default. You can enable the feature on an individual port
basis, in active or passive mode:
• Active mode – When you enable a port for active link aggregation, the port can exchange
standard LACP Protocol Data Unit (LACPDU) messages to negotiate trunk group configuration
with the port on the other side of the link. In addition, the port actively sends LACPDU
messages on the link to search for a link aggregation partner at the other end of the link, and
can initiate an LACPDU exchange to negotiate link aggregation parameters with an
appropriately configured remote port.
• Passive mode – When you enable a port for passive link aggregation, the port can exchange
LACPDU messages with the port at the remote end of the link, but the port cannot search for a
link aggregation port or initiate negotiation of an aggregate link. Thus, the port at the remote
end of the link must initiate the LACPDU exchange.
NOTE
Dell recommends that you disable or remove the cables from the ports you plan to enable for
dynamic link aggregation. Doing so prevents the possibility that LACP will use a partial configuration
to talk to the other side of a link. A partial configuration does not cause errors, but does sometimes
require LACP to be disabled and re-enabled on both sides of the link to ensure that a full
configuration is used. It's easier to disable a por t or remove its cable first. This applies both for active
link aggregation and passive link aggregation.
Examples of valid LACP trunk groups
Ports follow the same configuration rules for dynamically created aggregate links as they do for
statically configured trunk groups. Refer to “Trunk group rules” on page 312 and “Trunk group load
sharing” on page 314.
Figure 77 on page 325 shows some examples of valid aggregate links.
FIGURE 77 Examples of valid aggregate links
In this example, assume that link aggregation is enabled on all of the links between the device on
the left and the device on the right (which can be either a device or another vendor device). The
ports that are members of aggregate links in this example are following the configuration rules for
trunk links on devices.
The rules apply to a device even if the device at the other end is from another vendor and uses
different rules. Refer to “Trunk group rules” on page 312.
Configuration notes and limitations
This section lists the configuration considerations and limitations for dynamic link aggregation.
PowerConnect B-Series TI24X devices
The following notes and feature limitations apply to the PowerConnect B-Series TI24X devices:
• You cannot use 802.3ad link aggregation on a port configured as a member of a static trunk
group.
• The dynamic link aggregation ((802.3ad) implementation on PowerConnect B-Series TI24X
devices allows any number or ports up to eight to be aggregated into a link.